α-Pinene (1) is the most abundant monoterpene present in nature and plays crucial roles in many biological, atmospheric and industrial processes. Similar to many other readily accessed and biorenewable terpenes, α-pinene is widely used in both the fine chemical and polymer industries. More specifically, the Lewis acid-catalyzed polymerization of α-pinene (1), which generates polymer 2 (FIG. 8), has found a variety of uses in a plethora of industrial applications such as adhesives, plastics, and rubbers.
The high abundance, low cost, and biorenewability of α-pinene make its incorporation into additional novel materials highly desirable from the standpoint of sustainability. One avenue that has sparked some theoretical interest is the ring-opening metathesis polymerization (ROMP) of α-pinene (1). (Fomine, S.; Tlenkopatchev, M. A. Metathesis Transformations of Terpenes. Computational Modeling of (−)-α-Pinene Ring Opening by Ruthenium and Tungsten Carbene Catalysts. J. Organomet. Chem. 2012, 701, 68-74.) Unfortunately, it appears there have been no reports of α-pinene (1) participating in ROMP and, therefore, no polymers of this type (i.e., 3) are known. One factor believed contributing to the inability of α-pinene (1) to engage in ROMP is its highly congested trisubstituted olefin that likely hampers polymer initiation (and propagation).